motronic pistons

["Neil Cotie (EED)" <Neil.Cotie@domain.elided>]

Hi,

I would agree with Brian's comments about the Motronic pistons.

When I rebuild my 74 motor two or three years ago, I was building it based on advice from Tom Sahines, who (if I remember correctly) felt that the 10.5:1 Borgos and the 10:1 Motronics would give about the same results.

After having used the 10,5:1 Borgos I would say that if you have a choice between the two, definitely use the Motronic pistons.  
- They have lower compression for the same power (less tedency for pinging)
- they are stock and as such there is no question of the correct piston/liner clearance.  The values are in the manual.  Period.  My Borgo's arrived in the box with 50-100% more clearance than the stock pistons have according to the manual.  The problem is that I cannot get anyone in AE/Borgo (UK or Germany) to give me the recommended clearance, they just pass the buck.  So I used them anyhow and now I have an oil burning issue which *may* be related to the larger-than-usual clearance.  Hastings (ring manufacturer) have given me an opinion that this should not be the culprit, but time will tell.

Basically, the Motronics are stock and "well-known".  I wouldn't hesitate to use them.  However, as Tom advised me, put money into camshafts before putting money into pistons.

By the way, I should also point that Tom's advice was to replace the rings delivered with the pistons with Hastings rings, at least the oil control rings specifically.

Cheers,
Neil

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